Axial-flow fan motor

Abstract

A sleeve-type plain bearing of an axial-flow fan motor, made of sintered oilless metal, for bearing a rotation of a rotor has plural protrusions on a thrust bearing surface in a direction vertical to an axial direction of the rotor, and thereby lubricant impregnated in the sintered oilless metal is always supplied in spaces formed by the thrust bearing surface, the protrusions and a thrust plate provided on the rotation shaft.

What is claimed is: 
     
       1. An axial-flow fan motor comprising: a cylindrical-shaped housing forming an outer shell of the axial-flow fan motor;   a motor holder on a center part of said housing, said holder being held on said housing by a plurality of spokes and having a cylindrical boss part;   sleeve-type plain bearing means provided on said boss part of said motor holder, for bearing a rotation shaft of a rotor and having at least three protrusions spaced by substantially equal angles on a thrust bearing surface thereof, said sleeve-type plain bearing means being made of a sintered metal impregnated with oil; and   a thrust plate provided on said rotation shaft for sliding on said thrust bearing surface of said sleeve-type plain bearing;   said at least three protrusions producing positive pressure parts and negative pressure parts in an oil flow flowing between said thrust bearing surface and said thrust plate, thereby circulating the oil impregnated in said sleeve-type plain bearing means through said thrust bearing surface and said thrust plate.   
     
     
       2. An axial-flow fan motor in accordance with claim 1, wherein heights of said protrusions are in a range of 10-30 μm.   
     
     
       3. An axial-flow fan motor in accordance with claim 1, wherein inclination angles of said protrusions are in a range of 2-20 μm/mm.   
     
     
       4. An axial-flow fan motor in accordance with claim 1, wherein curvature of said protrusions in a direction parallel to an axial direction of said rotation shaft are at least 50 μm.   
     
     
       5. A bearing for an axial-flow motor, said bearing comprising: a bearing body made of sintered metal and impregnated with oil;   a thrust bearing surface disposed at one end of said bearing body;   a thrust plate which is to be fixed on a rotation shaft of said rotor; and   at least three protrusions disposed on said thrust bearing surface;   said at least three protrusions producing positive pressure parts and negative pressure parts in an oil flow flowing between said thrust bearing surface and said thrust plate, thereby circulating the oil impregnated in said bearing body through said thrust bearing surface and said thrust plate.   
     
     
       6. The bearing of claim 5, wherein heights of said protrusions are in a range of 10-30 μm. 
     
     
       7. The bearing of claim 5, wherein inclination angles of said protrusions are in a range of 2-20 μm/mm. 
     
     
       8. The bearing of claim 5, wherein curvature of said protrusions in a direction parallel to an axial direction of said rotation shaft are at least 50 μm. 
     
     
       9. The bearing of claim 5, wherein said protrusions are spaced by substantially equal angles on said thrust bearing surface.